The standardization of an image coding scheme called HEVC (High Efficiency Video Coding) by JCTVC (Joint Collaboration Team-Video Coding), which is a joint standardization organization of ITU-T and ISO/IEC, is currently under way for the purpose of improving coding efficiency more than H. 264/AVC (see, for example, Non-Patent Literature 1).
HEVC provides not only coding of a single layer but also scalable video coding, as in known image coding schemes such as MPEG2 and Advanced Video Coding (AVC). An HEVC scalable video coding technology is also called Scalable HEVC (SHVC) (for example, see Non-Patent Literature 2). The scalable video coding is generally a technology that hierarchically encodes a layer transmitting a rough image signal and a layer transmitting a fine image signal.
A first version of a standard specification of HEVC was published at the beginning of 2013, but extension of the specification has been continuously performed from various points of view such as enhancement of coding tools (for example, see Non-Patent Literature 3) in addition to the SHVC. Particularly, a technique called a sample adaptive offset (SAO) filter is applied from HEVC. In the SAO filter, the coding efficiency is improved by selecting an optimum mode among a plurality of modes based on a technique called a band offset and an edge offset.